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Old 04-08-2005, 05:08 PM
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Default RE: Hydrolock Help!


I had the same problem with my RC10GT a couple days ago.....(hydrolock is when the pull start won't pull because the piston is stuck in the cylinder, right?)

I ended up taking off the head and sliding the cylinder out and cleaning it up with some fine grade emory cloth.....for some reason the piston kept getting stuck when it got to the top of the cylinder.

I cleaned it for about 15 mins, put it back in and it was still sticking - but I could tell it wasn't as bad, so I cleaned it for about 15 more mins and it worked.
Nearly right, hydrolock is where there is an incompressible liquid - (fuel) in the combustion chamber. The engine cannot "turn over" because the piston cannot move any further up the sleeve as it cannot compress liquid, there is just too much pressure. As previously stated, it happens when there is too much fuel in the combustion chamber (too rich) and will prevent the piston from moving.

What i believe you are talking about is pinch, the sleeve is tapered (becomes narrower) at the highest point that the piston will reach during a combustion cycle (top dead centre). This provides a better seal between the piston and liner and aides compression, as fuel/air is less likely to be able to squeeze through the gap between the two components.
This is usually most noticeable in brand new engines, after run-in it usualy losens a bit as the piston/liner bed together.
If you could not turn the engine over at all (the piston got completely stuck) without the glow plug attached then you have solved the problem. If you mistook pinch for compression (you could not turn the engine over with the glow plug inserted) you may have ruined your engine (no compression, no combustion cycle).
If the piston did not got stuck, but only became harder to move at TDC, then you have removed the pinch and have more than likely shortened the life of your engine. It is there for a reason. Modifying the piston/liner without knowing exactlywhat you are doing, and how it will effect performance is never a good idea.

Hope you ticked box number one... Good luck.